In an automated manufacturing equipment for mass-producing products, the quality of the products is checked to distinguish between non-defective products and defective products, thereby preventing defective products from being distributed to a commodity distribution channel. In particular, with recent mass production of medical supplies and electronic components, there has been a demand not only for the improvement in performance of inspection devices for inspection of those products but also for higher accuracy and higher efficiency of sorters for sorting the products after inspection. Defective medical products affect the human life and this is a serious problem, and defective electronic components if incorporated in an electronic device prevents the electronic device to exhibit its performance to a satisfactory extent. Therefore, it has come to be required that the sorter is capable of sorting mass-produced products efficiently and with strict correctness and reliability to completely prevent inclusion of defective products among non-defective products.
Heretofore, as methods for sorting products after inspection into non-defective products and defective products, there have been known such a method using star wheels as shown in FIG. 9 and such a method using a pendulum as shown in FIG. 10.
In the former method using star wheels, as shown in FIG. 9, there are used a product conveying star wheel 3 which rotates while receiving products 1 in recesses 3a formed in its outer periphery, the products 1 being fed through a product inlet guide 2, and a product sorting star wheel 4 which is disposed adjacent the star wheel 3 and which is rotated so that recesses 4a formed in the outer periphery thereof come into alignment with the recesses 3a of the star wheel 3. Further, the recesses 4a of the product sorting star wheel 4 are contiguous to slits 4b for communication with a vacuum passage 5. When a defective product passes the star wheel 4, a negative pressure is generated in the vacuum passage 5 to attract the defective product to the star wheel 4 from the star wheel 3, whereby the defective product is discharged through a defective product discharge guide 6. On the other hand, in the case of a non-defective product, a negative pressure is not generated in the vacuum passage 5, so that the product 1 is conveyed as it is by the star wheel 3 and is sent out through a product outlet guide 6a.
On the other hand, in the latter method using a pendulum, there is used a pendulum 7 which is reciprocated pivotally about a pivot center O. The pendulum 7 is formed with first and second bifurcated passages 7a and 7b centered at the pivot center O. A pair of first and second discharge passages 9a and 9b is formed in a discharge guide 9. The discharge passages 9a and 9b each come into communication with either of the passage 7a or 7b in accordance with a swing motion of the pendulum 7. The pendulum 7 is allowed to swing according to whether each product 1 fed through a feed guide 8 is non-defective or defective, whereby the product 1 is introduced selectively into one of the first and second passages 7a and 7b and is then discharged through the first discharge passage 9a or the second discharge passage 9b.
However, in the conventional sorter using star wheels shown in FIG. 9, since the sorting of products 1 is performed by suction using a negative pressure, there exists an unstable factor relating to the generation and control of a required negative pressure, thus leading to the problem that the sorting operation is less reliable. moreover, the recesses 3a and 4a formed respectively in the outer periphery of the product conveying star-wheel 3 and in the outer periphery of the product sorting star wheel 4 are for receiving and sending out products 1, but since both of the recesses 3a and 4a are spaced a large distance at a certain pitch, it has been likely that at the time of sending out the products 1 through the defective product discharge guide 6 and the product outlet guide 6a and arranging them in order, the products 1 will suddenly approach each other into collision and that the resulting great impact on the products will cause damage to the products.
In the conventional method using a pendulum, which is shown in FIG. 10, since the pendulum 7 swings repeatedly with products 1 contained in its first and second passages 7a and 7b, the products 1 on the pendulum 7 may repeat mutual collision due to the action of repeated centrifugal forces. Also in this point there has been a fear of damage to the products 1. Besides, in the case where the number of products 1 contained in the first and second passages 7a and 7b changes, there is a fear that unevenness may occur in the swing motion of the pendulum 7 due to a change in inertia force associated with the swing motion. Thus, it has been difficult to ensure the stability in high-speed operation.